Student Projects
Contact Information
Country: United Kingdom
Year Submitted: 2018
University: University of Liverpool
List of Team Members (with year of graduation): Cameron Jones (2018)
Josh Healey (2018)
Mo Zamani (2018)
George Utley (2018)
Faculty Advisers: Mr. Dan Hibbert
Main Contact Email Address: sggutley@liverpool.ac.uk
Project Information
Title: Implementing a dynamic rolling road within University grounds with the use of NI instruments to allow dynamic testing of a Formula Student car.
Description: The purpose of this project is to implement dynamic rolling road testing facilities within the University workshops. Current facilities allow the use of rollers, however, no output can be captured. Using National Instrument’s equipment, the rollers can be used to record power data from the University of Liverpool Motorsport’s formula student car, allowing engine configuration and optimisation.
Products Used:
Software
- LabVIEW
Hardware
- CompactDAQ
- 9361 Module
- 9263 Module
- 9237 Module
1 The Challenge
Formula student is a highly competitive international competition and with dynamic events representing 67.5% of the total points awarded, it is crucial that the car is tested and optimised before the events to achieve the maximum possible dynamic score. A main factor of this optimisation is mapping the ECU for the event to achieve maximum engine performance. This requires a roller system to record data which then allows configuration of engine settings to achieve the performance the team desires (i.e. power, efficiency etc.). Previously the team would outsource this task. However, the University contains the facilities to perform these tests in house.
Before the use of NI equipment, the University possessed a roller system that provided no data output. The team’s challenge was to implement NI equipment in order to obtain data outputs (i.e. torque and angular speed) that allows the optimal configuration of the ECU. This project will, in the future, allow the team to test and configure the cars performance in house before competition whilst providing the information to allow members to improve their knowledge on engine performance.
Future electronic implementations for the Formula Student car include Drive-by-wire throttle control and electronic clutch control. These systems will improve the car’s dynamic performance in various events drastically. These systems open up the possibility for different modes of operation, such as launch control in the acceleration event at competition. The output received from a dynamic rolling road on University grounds will help the team to configure these systems and reduce the lead time for completion.
2 The Solution
2.1 Implementation of Hardware
In order to produce data outputs from the rollers, several pieces of NI hardware were used. Firstly, a CompactDAQ system is used to connect to the team’s laptop. Three I/O modules are then connected to the CompactDAQ, providing the sensory inputs needed to record and produce test data and outputs needed to control the rollers.
The modules used within the cDAQ are as follows;
1) 9263 C-Series Module: Used as an analogue output to control rolling road motor. This module is the only output module within the system and provides the input connection between the NI instruments and the rolling road motor.
2) 9201 C-Series Module: Used as an analogue input for the data from the torque arm load cell. The torque arm connected to the rolling road rollers provides a sensory output which is connected to the module. This acts as an input signal which allows torque to be recorded once the system has been calibrated. The torque from recording taken from the rollers can be converted to torque at the wheels using the ratio of radii i.e.
3) 9361 C-Series Module: Used as an analogue input with clocking capability for the rotary encoder on the rolling rode rollers. The sensors on this module are used to measure rotating speed directly from the rollers. This rotary speed at the rollers can be converted to rotary speed at the wheels assuming no slippage and again using a ratio of radii i.e.
A 4kHz minimum clock speed was calculated by considering the highest practical speed that the car will achieve on the rollers, this was based on estimates from the car around track and a value of 70mph was selected. The calculation also needed to factor in the size of the respective wheels. The ULM vehicle wheels are approximately 508mm in diameter and the roller diameter is 1.25m. Assuming no slip or losses the two wheels when in contact will rotate at the same rate.
The rotational velocity of the wheel was calculated as follows:
Then by considering the ratios of the two wheels the RPS of the roller can be calculated:
Based on the assumption that the encoder tape used on the roller is a 1000 pulse per revolution encoder, meaning that for each revolution it will generate 1000 signals. This gave a pulse rate of 4000 pulses per second and therefore required the card to be capable of recording at 4000 pulses per second or 4kHz.
This hardware provides all the necessary data needed to process performance observation. The inputs/outputs of the system must be coded such that meaningful data can be processed. This part of the project was completed on the software LabVIEW.
2.2 Use of Software
The CompactDAQ would be controlled via remote desktop from the team’s laptop. This was done so the hardware could still be accessed if it was installed onto the car without the need of an external monitor – ideal for competition. Both LabView and DAQmx were used to code the dynamometer set up for the University of Liverpool Formula Student Team. Initially – due to the date when the hardware received – both LabView and DAQmx were 2014 versions. These had to be updated in order to discover all modules (specifically NI-9361) we wished to use on the CompactDAQ. As the team had little experience coding specific NI modules, the NI example finder was used to give examples about how the modules had been previously coded, which would influence our approach to coding them. The wizard was initially used to code the modules, however after input of NI engineers, the explained and showed the team the advantage of coding the modules from scratch. NI-9263 was coded to allow us to control the output signal given by the CompactDAQ. The control panel has a dial allowing the use to control the output signal (0-10v). It was important to ensure after the script had stopped, the voltage was set back to zero again. The load cell (NI-9237) - which had a simpler task - was mostly coded using the calibrated DAQ-assistant. The control panel was initially set up to show a graph of the load being produce in order to ensure it was functioning correctly. The encoder was coded to RPM of the rolling road. The coding for this module requires further input from an NI engineer to ensure it will function as required. The display panel will display a power output of the engine in the form of a graph (power vs time) which will be achieved through a simple multiplication of the RPM and torque output (of the load cell). The script functions within a while loop in order to be able to record the data over a set amount of time.
2.3 Level of Completion
The progress of the rolling road has been rapid over the last year in comparison with previous years due to the support of National Instruments. The coding for on LabVIEW is nearing the final stages which will allow sensory data gathered from the three modules to be processed into meaningful recorded data. Once the coding is complete, the system can be calibrated with known torques and rotational speeds which will then see the system to competition. This will then allow the team to fully test the powertrain and drivetrain components of the car within University facilities, raising our chances of higher performance in competition. The data outputs from these tests will allow the team to develop components such as the ECU, sprocket and gearbox in future iterations, maintaining performance development.
2.4 Time to Build
The project began in September 2017. It is expected that the rolling road will be fully running by the end of 2018, giving a project span of 15 months.
2.5 Additional Revisions that could be made
Additionally, further sensors could be incorporated into the dynamometer to improve test results. For example, sensors incorporated into the exhaust fume extractor will allow the monitoring of air/fuel ratio. This will therefore give further test results and allow more optimisation of power/drivetrain settings.
